Pneumatic transportation of materials and apparatus therefor

ABSTRACT

A machine for the pneumatic transportation of material in which the material to be transported is sucked downwardly along an inclined passage part of which is in the form of a suction chamber having an upper material inlet and a lower material outlet. An air outlet leads from the suction chamber, the axis of the outlet being transverse to the axis of the passage. An air displacing device such as a fan has its inlet aligned with and connected to the air outlet from the chamber. The pressure side of the fan is connected to a device such as a venturi to which the material which has passed from the suction chamber through the lower outlet is also fed, the air and material then flowing from the venturi device along a delivery duct. The suction chamber has therein arrangements for the removal of fines from the air flowing towards the air outlet.

United States Patent [15] 3,656,811 [451 Apr. 18, 1972 Raad [s41 PNEUMATIC TRANSPORTATION OF MATERIALS AND APPARATUS THEREFOR [72] Inventor: Ralph R. Raad, 8 Astoria Main Road, Three Anchor Bay, Republic of South Afr ca" A a v We. 22 Filed: Nov. 13, 1969 [21] Appl.N0.: 876,271

[30] Foreign Application Priority Data Nov. 18, 1968 South Africa .68/17515 [52] U.S.Cl ..302/23 [51] Int. Cl ..B65g53/04 [58] FieldofSearch.... ..302/23,37

[56] References Cited UNITED STATES PATENTS 908,445 1/1909 Carlton ..302/23 2,719,057 9/1955 Gamper ..302/23 FOREIGN PATENTS OR APPLICATIONS 709,606 5/1954 Great Britain ..302/23 1,099,520 3/1955 France ..302/23 ABSTRACT A machine for the pneumatic transportation of material in which the material to be transported is sucked downwardly along an inclined passage part of which is in the form of a suction chamber having an upper material inlet and a lower material outlet. An air outlet leads from the suction chamber, the axis of the outlet being transverse to the axis of the passage. An air displacing device such as a fan has its inlet aligned with and connected to the air outlet from the chamber. The pressure side of the fan is connected to a device such as a venturi to which the material which has passed from the suction chamber through the lower outlet is also fed, the air and material then flowing from the venturi device along a delivery duct. The suction chamber has therein arrangements for the removal of fines from the air flowing towards the air outlet.

16 Claims, 6 Drawing Figures PATENTEDAPR 18 I972 SHEET 2 BF 2 EICLB.

PNEUMATIC TRANSPORTATION OF MATERIALS AND APPARATUS THEREFOR BACKGROUND TO INVENTION Apparatus has been proposed for the pneumatic transportation of materials and the main object of the present invention is to provide apparatus of this kind which is readily transportable and which can rapidly transport a variety of materials such as coal and grain products. The main problems besetting prior apparatus of this kind are the low rates of transportation possible i.e. only relatively small quantities have been transportable within a given time, the low efficiency of the apparatus, and the rapid wear of the air displacing device (usually a rotary fan) and its bearings which occurs as a result of the ingress into the fan and its bearings of fines and even large pieces of material. This is, obviously, a particular problem if coal is being transported.

SUMMARY OF INVENTION This invention relates to apparatus for the pneumatic transportation of solid material.

According to the invention there is provided apparatus for the pneumatic transportation of solid material, the apparatus including means for separating said material from the conveying air stream, the separating means comprising a material conveying passage along which the material passes, a suction chamber forming part of said passage, and an outlet from said chamber the axis of which is disposed transversely to the longitudinal axis of said passage, the apparatus further including an air displacing device having a suction inlet aligned with and connected to said outlet from said chamber so that air leaving said chamber enters the air displacing device without any substantial change of direction.

The passage is preferably inclined, and means are provided for dividing said chamber into upper and lower parts whereby the bulk of the material enters said lower part and fines and air enter the upper part.

Said outlet can be connected to said upper chamber part and vanes can be provided in said upper chamber part for imparting whirling motion to the air flowing towards said outlet.

Preferably, a cone is provided betweensaid vanes and the outlet, the cone being arranged with its base towards the outlet and serving to force whirling air to flow radially before clearing the base of the cone and entering said outlet, thearrangement of the base of the cone with respect to the outlet being such that the flowing air must perform a sharp change in direction around the base of the cone. In this constructional form, a ring of vanes is provided between the outlet and the base of the cone for imparting further swirling motion to the flowing air.

Said dividing means can effectively be extended in the upstream direction from said chamber by means of a plurality of deflector plates arranged so as to permit passage of air therebetween and thence to said upper chamber part while inhibiting passage therebetween of material which thus flows to said lower chamber part. In this form, the part of the passage upstream of said chamber diverges towards said chamber and said deflector plates are in the divergent passage part, and wherein the material conveying airstream is caused to enter the passage part below the deflector plates.

Desirably, air entering said lower chamber part with the bulk of the material is separated from the material by placing said outlet and said lower chamber part in communication via the downstream end of the lower chamber part. The dividing means can be a plate, the edge at said downstream end of said lower part being so positioned that air flowing out of said lower chamber part is forced to perform a turn of substantially 360 about said edge before flowing towards said outlet. An adjustable bafile can be provided for controlling the gap through which said downstream end of said lower chamber part and said outlet are in communication. The baffle is desirably positioned so as to lie in the outer periphery of the particles of material thrown to the outer periphery of said turning airstream. Said plate preferably divides one lateral part of said chamber into said upper and lower chamber parts, the other lateral part of said chamber being undivided and said outlet leading from said other lateral part, there being a spiral scroll for simultaneously conveying laterally, and imparting a whirling motion to, air which is drawn from said lower chamber part about said edge of said plate. In this constructional form, a guard is provided around said outlet for preventing material entrained in the air guided in a lateral and spiral path by said scroll from passing directly through said outlet.

The part of the guard which faces said gap is formed with a recess positioned so as to intercept particles entrained in said turning airstream and direct them downwardly.

A chute can lead from said other lateral part of said chamber, the chute serving to receive fines separated from the airstream and for conveying these fines to a position downstream of said edge of said plate.

Air inlet means can be provided for permitting supplementary air to enter said chamber, the area of said inlet means being variable.

According to a further aspect of the invention there is provided a method for the pneumatic transportation of solid material, the method including sucking the material to be transported into a material conveying passage part of which is in the form of a suction chamber, the material passing through the suction chamber, sucking air from said chamber through an outlet from said chamber the axis of which is disposed transversely to the longitudinal axis of said passage and into an air displacing device having its inlet aligned with and connected to said outlet so that between said outlet and inlet the air does not undergo any substantial change in direction, and causing material to be discharged from said passage after separation from the conveying air.

SPECIFIC DESCRIPTION For a better understanding of the present invention and to show how the same may be carried into effect reference will now be made, by way of example, to the accompanying drawings in which:

FIG. 1 is a side view of apparatus for the pneumatic transportation of material,

FIG. 2 is a front view, partly in section, of the apparatus of FIG. 1,

FIGS. 3 to 5 are sections on the lines III-Ill, IVIV and V-V of FIG. 1, and

FIG. 6 is a section on the line Vl-VI in FIG. 5.

Referring firstly to FIGS. 1 and 2, the pneumatic transportation apparatus illustrated is generally referenced 10 and includes a material conveying passage generally indicated at 12 which is straight and which slopes downwardly in the direction in which air and materials flow. Thepassage 12 includes an inlet duct 14 which is connected to a source (not shown) of the material to be transported, an outlet duct 16 and, intermediate the ducts l4 and 16, a suction chamber 18. The chamber 18 has a lateral outlet 20 (FIG. 2) transverse to the direction of elongation of the passage 12. The outlet 20 leads to a centrifugal fan 22 having an outlet 24 connected to an outlet duct 26.

The ducts 16 and 26 lead to a venturi device 28, the device 28 being generally axially aligned with the duct 26 and with a diverging outlet duct 30, and the duct 16 leading into the low pressure throat of the device 28. The device 28 can, if desired, be replaced by an arrangement in which the material is discharged through a central noule surrounded by an annular air flow passage.

The function of the chamber 18 is to separate the material being transported from the transporting air in such manner that the air is drawn through the fan 22 and the material passes through the chamber 18 to the duct 16, the material rejoining the flowing air at the device 28. By excluding the material airstream turning about said edge so as to intercept heavier from the fan, the life of the fanis greatly prolonged.

The inlet duct 14 is divergent and forms a diffuser, there being a series of deflector plates 32 along the length of the duct 14. The arrangement of the plates 32 is such that while air tends to pass therethrough, as indicated by arrows A, they tend to deflect material downwardly and prevent its passage therethrough. Some fines, however, pass between the plates 32 with the air.

The right hand part of the chamber 18, as viewed in FIG. 2, is divided by a plate 34 (FIG. 1) into upper and lower chamber parts. The plate 34 is generally aligned with the plates 32 so that air and fines which pass between the plates 32 pass into the upper chamber part and the bulk of the material passes into the lower chamber part.

The upper chamber part has therein a deflecting plate 36 (FIG. which diverts the flowing air and fines laterally so that they flow towards vanes 38 and a cone 40. The vanes 38 impart a swirling motion to the air so that the fines, under the action of centrifugal force, are thrown outwardly and pass around the periphery of the cone 40 (see arrows B in FIGS. 4 and 5). The cone 40 has a central aperture 42 (FIG. 6) through which the substantially clean air at the centre of the whirling stream passes directly to the outlet 20. The air carrying the fines, once it has cleared the periphery of the cone 40, must make a hairpin change of direction before it can pass through a further ring of vanes 44 and reach the outlet 20 (see arrows B in FIGS. 4 and 5). This sudden change of flow direction, and the swirling motion imparted by the vanes 38, has the efiect of separating substantially all the remaining fines from the air so that the fines ladened air which initially passed between the plates 32 is substantially free of fines before it reaches the outlet 20. The path followed by the fines after separation from the air will be discussed later.

The bulk of the material passes beneath the plate 34 and continues along the section 16 towards the device 28. The suction effect of the fan 22 is applied to the duct 16 via the gap 46 (FIGS. 1 and 6) which exists between the lower edge of the plate 34 and a baffle 48. The baffle is secured to the casing of the chamber 18 by means of wing nuts 50 which permit the baffle to be secured in any desired position so that the width of the gap 46 can be varied at will.

Air which is drawnthrough the gap 46 (as indicated by arrows C in FIGS. 1 and 3) undergoes a 360 change in direction and this change in direction has the effect of removing from this air the heavier of the fines which it has entrained. The baffle 48 plays a part in the cleaning of the air stream for the bulk of the fines are at the outer periphery of the turning air stream and these fines impinge on the baffle 48 as indicated by D in FIG. 1.

As will clearly be seen from FIGS. 3 to 5, the air and material emerging from beneath the plate 34 is in the right hand part of the chamber 18 whereas the outlet 20 is on the left. To displace the air smoothly from right to left and at the same time time impart a swirling motion thereto, there is provided a spiral scroll 52 which has a circumferential extent of about 150 and which continuously diminishes in width. The maximum width of the scroll 52 can be seen in FIG. 3.

A guard 54 (see FIGS. 3 to 6) is provided around the outlet 20 to prevent solid material from passing directly through the outlet under the action of the laterial motion imparted to the air stream by the scroll 52. The guard 54 is L-shaped in section and, while circular over approximately half its periphery, is extended at 56 (FIG. 6) towards the gap 46. The extension 56 is so formed as to provide a recess 58 which faces the gap 44. The effect of this recess is to intercept and direct downwardly (see arrow D in FIG. 6) a proportion of the fines. The bulk of the fines not intercepted by the bafile 48 and recess 58 follows the path indicated by arrows E. The air enters the outlet 20 between the vanes 44 as indicated by arrows F.

It will be understood from the above description that the bulk of the fines are removed from the air before it enters the outlet 20. Theremoved fines all drop down on the right hand side of the chamber 18 and a chute 60 is provided which receives these fines and leads them sufliciently far down the duct 16 so that they are not picked-up by air flowing beneath fhezplate 34 (as indicated by arrow C) and carried to the out- A supplementary air inlet 62 is provided into the chamber 18, vanes 64 directing the air flow through the inlet 62 and there being an adjustable shutter 66 for controlling the area of the inlet 62. Air admitted through the inlet 62 lessens the suction on the duct 14 and increases the delivery pressure in the duct 26. In use, the position of the battle 48 and of the shutter 66 are regulated in dependance on the nature of the material being transported so as to obtain maximum rates of transportation with optimum fines removal from the air.

The duct 14 can be connected to an elbow of inverted U- shape by means of a pivotal connection. Thus the intake nozzle faces downwardly and can suck material from an overhead hopper.

In a further constructional form (not shown), the outlet 24 can be connected to the suction side of a further fan and the pressure side of the further fan connected to the device 28. In this form the air intake of the further fan is derived partly from the outlet of the fan 22 and partly from atmosphere. Alternatively, the fan 22 can blow to atmosphere and the further fan have its suction side open to atmosphere.

To improve the separation of the larger pieces of material from the air, the passage 12 can be curved so that the flowing material is subjected to the action centrifugal force which tends to throw it outwardly (i.e. generally to the right in FIG. 1) and minimise the possibility of it reaching the outlet 20.

The cone 40 can, if desired, be slightly tilted and the ring of vanes 44 can be replaced by a partial ring of vanes extending around the left hand part of the outlet 20 when the apparatus is viewed as in FIG. 6).

In a further constructional form, an outlet 20 can be arranged on each side of the chamber 18, the outlets being axially aligned and the illustrated internal arrangement of the chamber 18 being duplicated so that the air flow is divided and lead into two fans 22.

I claim:

1. Apparatus for the pneumatic transportation of solid material, the apparatus comprising:

a. A material conveying passage along which the material passes, said passage being inclined, I

b. A suction chamber forming part of said passage,

c. An outlet from said chamber the axis of which is disposed transversely to the longitudinal axis of said passage,

(1. An air displacing device having a suction inlet aligned with and connected to said outlet from said chamber so that air leaving said chamber enters the air displacing device without any substantial change of direction e. A longitudinally extending divider plate provided for dividing said chamber into upper and lower parts whereby the bulk of the material enters said lower part and fines and air enter the upper part, said outlet leading from said upper part, and

f. means for causing the air flowing towards said outlet to follow a path which promotes separation of fines from the arr.

2. Apparatus as claimed in claim 1, wherein the dividing plate is effectively extended in the upstream direction from said chamber by means of a plurality of deflector plates arranged so as to permit passage of air therebetween and thence to said upper chamber part while inhibiting passage therebetween of material which thus flows to said lower chamber part.

3. Apparatus as claimed in claim 2, wherein the part of the passage upstream of said chamber diverges towards said chamber and said deflector plates are in the divergent passage part, and wherein the material conveying airstream is caused to enter the passage part below the deflector plates.

4. Apparatus as claimed in claim 1, wherein air entering said lower chamber part with the bulk of the material is separated from the material by placing said outlet and said lower chamber partin communication via the downstream end of the lower chamber part.

5. Apparatus as claimed in claim 4, wherein said dividing means is a plate and wherein the edge of the plate at said downstream end of said lower chamber part is so positioned that air flowing out of said lower chamber part is forced to perform a turn of substantially 360 about said edge before flowing towards said outlet.

6. Apparatus as claimed in claim 5, and including an adjustable baffle controlling the gap through which said downstream end of said lower chamber part and said outlet are in communication.

7. Apparatus as claimed in claim 6, wherein said bafile is positioned so as to lie in the outer periphery of the airstream turning about said edge so as to intercept heavier particles of material thrown to the outer periphery of said turning airstream.

8. Apparatus as claimed in claim 5, wherein said plate divides one lateral part of said chamber into said upper and lower chamber parts, the other lateral part of said chamber being undivided and said outlet leading from said other lateral part, there being a spiral scroll for simultaneously conveying laterally, and imparting a whirling motion to, air which is drawn from said lower chamber part about said edge of said late. p 9. Apparatus as claimed in claim 8, wherein a guard is provided around said outlet for preventing material entrained in the air guided in a lateral and spiral path by said scroll from passing directly through said outlet.

10. Apparatus as claimed in claim 9 wherein the part of the guard which faces the gap through which said downstream end of said lower chamber part and said outlet are in communication is formed with a recess positioned so as to intercept particles entrained in said turning airstream and direct them downwardly. v

11. Apparatus as claimed in claim 8, and including a chute leading from said other lateral part of said chamber, the chute serving to receive fines separated from the airstream and for conveying these fines to a position downstream of said edge of said plate.

12. Apparatus as claimed in claim 1, and including air inlet means for permitting supplementary air to enter said chamber, the area of said inlet means being variable.

13. A method for the pneumatic transportation of solid material, the method including sucking the material to be transported into an inclined material conveying passage part of which is in the form of a suction chamber, the material passing through the suction chamber, sucking air and fines from an upper part of said chamber through an outlet from said chamber the axis of which is disposed transversely to the longitudinal axis of said passage and into an air displacing device having its inlet aligned with and connected to said outlet so that between said outlet and inlet the air does not undergo any substantial change in direction, causing the fines laden air to follow a path which promotes separation of fines from the air, and causing material to be discharged from said passage after separation from the conveying air.

14. Apparatus for the pneumatic transportation of solid material, the apparatus comprising a material conveying passage along which the material passes, a suction chamber forming part of said passage, an outlet from said chamber the axis of which is disposed transversely to the longitudinal axis of said passage, an air displacing device having a suction inlet aligned with and connected to said outlet from said chamber so that air leaving said chamber enters the air displacing device without any substantial change of direction, said passage being inclined and there being a longitudinally extending divider plate provided for dividing said chamber into lower and upper parts whereby the bulk of the material enters said lower part and fines and air enter the upper part, said outlet being connected to said upper chamber part and there being vanes provided in said upper chamber for imparting whirling motion to the air flowing towards said outlet.

15. Apparatus as claimed in claim 14, and including a cone between said vanes and the outlet, the cone being arranged with its base towards the outlet and serving to force whirling air to flow radially before clearing the base of the cone and entering said outlet, the arrangement of the base of the cone with respect to the outlet being such that the flowing air must perform a sharp change in direction around the base of the cone.

16. Apparatus as claimed in claim 15, and including a ring of vanes between the outlet and the base of the cone for imparting further swirling motion to the flowing air. 

1. Apparatus for the pneumatic transportation of solid material, the apparatus comprising: a. A material conveying passage along which the material passes, said passage being inclined, b. A suction chamber forming part of said passage, c. An outlet from said chamber the axis of which is disposed transversely to the longitudinal axis of said passage, d. An air displacing device having a suction inlet aligned with and connected to said outlet from said chamber so that air leaving said chamber enters the air displacing device without any substantial change of direction, e. A longitudinally extending divider plate provided for dividing said chamber into upper and lower parts whereby the bulk of the material enters said lower part and fines and air enter the upper part, said outlet leading from said upper part, and f. means for causing the air flowing towards said outlet to follow a path which promotes separation of fines from the air.
 2. Apparatus as claimed in claim 1, wherein the dividing plate is effectively extended in the upstream direction from said chamber by means of a plurality of deflector plates arranged so as to permit passage of air therebetween and thence to said upper chamber part while inhibiting passage therebetween of material which thus flows to said lower chamber part.
 3. Apparatus as claimed in claim 2, wherein the part of the passage upstream of said chamber diverges towards said chamber and said deflector plates are in the divergent passage part, and wherein the material conveying airstream is caused to enter the passage part below the deflector plates.
 4. Apparatus as claimed in claim 1, wherein air entering said lower chamber part with the bulk of the material is separated from the material by placing said outlet and said lower chamber part in communication via the downstream end of the lower chamber part.
 5. Apparatus as claimed in claim 4, wherein said dividing means is a plate and wherein the edge of the plate at said downstream end of said lower chamber part is so positioned that air flowing out of said lower chamber part is forced to perform a turn of substantially 360* about said edge before flowing towards said outlet.
 6. Apparatus as claimed in claim 5, and including an adjustable baffle controlling the gap through which said downstream end of said lower chamber part and said outlet are in communication.
 7. Apparatus as claimed in claim 6, wherein said baffle is positioned so as to lie in the outer periphery of the airstream turning about said edge so as to intercept heavier particles of material thrown to the outer periphery of said turning airstream.
 8. Apparatus as claimed in claim 5, wherein said plate divides one lateral part of said chamber into said upper and lower chamber parts, the other lateral part of said chamber being undivided and said outlet leading from said other lateral part, there being a spiral scroll for simultaneously conveying laterally, and imparting a whirling motion to, air which is drawn from said lower chamber part about said edge of said plate.
 9. Apparatus as claimed in claim 8, wherein a guard is provided around said outlet for preventing material entrained in the air guided in a lateral and spiral path by said scroll from passing directly through said outlet.
 10. Apparatus as claimed in claim 9 wherein the part of the guard which faces the gap through which said downstream end of said lower chamber part and said outlet are in communication is formed with a recess positioned so as to intercept particles entrained in said turning airstream and direct them downwardly.
 11. Apparatus as claimed in claim 8, and including a chute leading from said other lateral part of said chamber, the chute serving to receive fines separated from the airstream and for conveying these fines to a position downstream of said edge of said plate.
 12. Apparatus as claimed in claim 1, and including air inlet means for permitting supplementary air to enter said chamber, the area of said inlet means being variable.
 13. A method for the pneumatic transportation of solid material, the method including sucking the material to be transported into an inclined material conveying passage part Of which is in the form of a suction chamber, the material passing through the suction chamber, sucking air and fines from an upper part of said chamber through an outlet from said chamber the axis of which is disposed transversely to the longitudinal axis of said passage and into an air displacing device having its inlet aligned with and connected to said outlet so that between said outlet and inlet the air does not undergo any substantial change in direction, causing the fines laden air to follow a path which promotes separation of fines from the air, and causing material to be discharged from said passage after separation from the conveying air.
 14. Apparatus for the pneumatic transportation of solid material, the apparatus comprising a material conveying passage along which the material passes, a suction chamber forming part of said passage, an outlet from said chamber the axis of which is disposed transversely to the longitudinal axis of said passage, an air displacing device having a suction inlet aligned with and connected to said outlet from said chamber so that air leaving said chamber enters the air displacing device without any substantial change of direction, said passage being inclined and there being a longitudinally extending divider plate provided for dividing said chamber into lower and upper parts whereby the bulk of the material enters said lower part and fines and air enter the upper part, said outlet being connected to said upper chamber part and there being vanes provided in said upper chamber for imparting whirling motion to the air flowing towards said outlet.
 15. Apparatus as claimed in claim 14, and including a cone between said vanes and the outlet, the cone being arranged with its base towards the outlet and serving to force whirling air to flow radially before clearing the base of the cone and entering said outlet, the arrangement of the base of the cone with respect to the outlet being such that the flowing air must perform a sharp change in direction around the base of the cone.
 16. Apparatus as claimed in claim 15, and including a ring of vanes between the outlet and the base of the cone for imparting further swirling motion to the flowing air. 